1. Field of the Invention
The present invention relates to an adapter, or holder, for detachably mounting a dial indicator on a spindle such as may be found on milling machines and other machine tools. More particularly, the invention concerns an adapter which permits rotation of the dial indicator relative to the workpiece without the necessity of rotating the spindle.
2. Discussion of the Prior Art
It is a well known practice to mount a dial indicator on the spindle of a milling machine or on the headstock of a lathe to measure concentricity or position of a workpiece with respect to the axis of rotation of the mill or lathe.
Various types of adapters or holders have been suggested to enable interconnection of dial indicators with the spindles of machine tools. Certain of the prior are adapters are concerned primarily with improved mechanisms for attaching the dial indicator to the spindle. The patent to Arnold U.S. Pat. No. 3,542,323 is exemplary of such art.
Other prior art holders are directed to providing mechanisms for radical displacement of the feeler elements with respect to the axis of rotation of the spindle. The patent to Muller U.S. Pat. No. 3,601,997 discloses such a device.
Still other prior art holders are primarily concerned with providing mechanisms which permit pivotal or swinging movement of the holder elements with respect to the workpiece. Such devices are shown in the patents to Lock U.S. Pat. No. 4,439,925 and to Steineman U.S. Pat. No. 3,167,866.
Common to all of the prior art holders, or adapters, is the requirement that the spindle of the machine be rotated as the dial indicator measurements are made. Because of the difficulty in rotating the spindle by hand, as is the case in many types of large machines, this requirement is highly undesirable. Further, rotation of the spindle, either by hand or by actuation of the motor, can be quite dangerous.
The aforementioned drawback of the prior art devices is uniquely overcome by the present invention. Due to the novel design of the adapter of the present invention, the dial indicator can readily be attached to the spindle and can then be effortlessly rotated relative to the workpiece by hand while the spindle remains absolutely stationary.